Feature custom ToSchema rename (#354)

Add support for custom `rename` and `rename_all` attribute on `ToSchema`
derived types. These attributes work like the serde counter parts can be used
instead of serde ones. But if both are defined then serde `rename` and `rename_all`
will take prededence.

Add support for `title` attribute for `ToSchema` derived types. Currently there
is one limitation with `title` and it cannot be put on complex enum because of 
limitations in types used to generate OpenAPI spec. in `utoipa`.

Update docs and add more examples regarding rename and title on `ToSchema`.
Add tests for possible configuration options.

Refactor `ToSchema`  enum `ToTokens` functionality once more to simplify it.

utoipa-gen/src/component.rs

@@ -310,16 +310,10 @@ trait Rename {
 /// * `container_rule` which is used to rename containers with _`rename_all`_ property.
 fn rename<'r, R: Rename>(
     value: &'r str,
-    to: Option<&'r str>,
+    to: Option<Cow<'r, str>>,
     container_rule: Option<&'r RenameRule>,
 ) -> Option<Cow<'r, str>> {
-    let rename = to.as_ref().and_then(|to| {
-        if !to.is_empty() {
-            Some(Cow::Borrowed(*to))
-        } else {
-            None
-        }
-    });
+    let rename = to.and_then(|to| if !to.is_empty() { Some(to) } else { None });
 
     rename.or_else(|| {
         container_rule

utoipa-gen/src/component/features.rs

@@ -558,9 +558,13 @@ impl ToTokensExt for Vec<Feature> {
 pub trait FeaturesExt {
     fn pop_by(&mut self, op: impl FnMut(&Feature) -> bool) -> Option<Feature>;
 
-    fn find_value_type_feature_as_value_type(&mut self) -> Option<super::features::ValueType>;
+    fn pop_value_type_feature(&mut self) -> Option<super::features::ValueType>;
 
-    fn find_rename_feature_as_rename(&mut self) -> Option<Rename>;
+    /// Pop [`Rename`] feature if exists in [`Vec<Feature>`] list.
+    fn pop_rename_feature(&mut self) -> Option<Rename>;
+
+    /// Pop [`RenameAll`] feature if exists in [`Vec<Feature>`] list.
+    fn pop_rename_all_feature(&mut self) -> Option<RenameAll>;
 }
 
 impl FeaturesExt for Vec<Feature> {
@@ -570,36 +574,49 @@ impl FeaturesExt for Vec<Feature> {
             .map(|index| self.swap_remove(index))
     }
 
-    fn find_value_type_feature_as_value_type(&mut self) -> Option<super::features::ValueType> {
+    fn pop_value_type_feature(&mut self) -> Option<super::features::ValueType> {
         self.pop_by(|feature| matches!(feature, Feature::ValueType(_)))
             .and_then(|feature| match feature {
                 Feature::ValueType(value_type) => Some(value_type),
                 _ => None,
             })
     }
 
-    fn find_rename_feature_as_rename(&mut self) -> Option<Rename> {
+    fn pop_rename_feature(&mut self) -> Option<Rename> {
         self.pop_by(|feature| matches!(feature, Feature::Rename(_)))
             .and_then(|feature| match feature {
                 Feature::Rename(rename) => Some(rename),
                 _ => None,
             })
     }
+
+    fn pop_rename_all_feature(&mut self) -> Option<RenameAll> {
+        self.pop_by(|feature| matches!(feature, Feature::RenameAll(_)))
+            .and_then(|feature| match feature {
+                Feature::RenameAll(rename_all) => Some(rename_all),
+                _ => None,
+            })
+    }
 }
 
 impl FeaturesExt for Option<Vec<Feature>> {
     fn pop_by(&mut self, op: impl FnMut(&Feature) -> bool) -> Option<Feature> {
         self.as_mut().and_then(|features| features.pop_by(op))
     }
 
-    fn find_value_type_feature_as_value_type(&mut self) -> Option<super::features::ValueType> {
+    fn pop_value_type_feature(&mut self) -> Option<super::features::ValueType> {
+        self.as_mut()
+            .and_then(|features| features.pop_value_type_feature())
+    }
+
+    fn pop_rename_feature(&mut self) -> Option<Rename> {
         self.as_mut()
-            .and_then(|features| features.find_value_type_feature_as_value_type())
+            .and_then(|features| features.pop_rename_feature())
     }
 
-    fn find_rename_feature_as_rename(&mut self) -> Option<Rename> {
+    fn pop_rename_all_feature(&mut self) -> Option<RenameAll> {
         self.as_mut()
-            .and_then(|features| features.find_rename_feature_as_rename())
+            .and_then(|features| features.pop_rename_all_feature())
     }
 }
 

utoipa-gen/src/component/into_params.rs

@@ -257,22 +257,16 @@ impl ToTokens for Param<'_> {
                 field_features.push(style.clone()); // could try to use cow to avoid cloning
             };
         }
-        let value_type = field_features.find_value_type_feature_as_value_type();
+        let value_type = field_features.pop_value_type_feature();
         let is_inline = field_features
             .pop_by(|feature| matches!(feature, Feature::Inline(_)))
             .is_some();
         let rename = field_features
-            .find_rename_feature_as_rename()
+            .pop_rename_feature()
             .map(|rename| rename.into_value());
-        let rename = field_param_serde
+        let rename_to = field_param_serde
             .as_ref()
-            .and_then(|field_param_serde| {
-                if !field_param_serde.rename.is_empty() {
-                    Some(Cow::Borrowed(field_param_serde.rename.as_str()))
-                } else {
-                    None
-                }
-            })
+            .and_then(|field_param_serde| field_param_serde.rename.as_deref().map(Cow::Borrowed))
             .or_else(|| rename.map(Cow::Owned));
         let rename_all = self
             .serde_container
@@ -283,8 +277,8 @@ impl ToTokens for Param<'_> {
                     .rename_all
                     .map(|rename_all| rename_all.as_rename_rule())
             });
-        let name = super::rename::<FieldRename>(name, rename.as_deref(), rename_all)
-            .unwrap_or(Cow::Borrowed(name));
+        let name =
+            super::rename::<FieldRename>(name, rename_to, rename_all).unwrap_or(Cow::Borrowed(name));
         let type_tree = TypeTree::from_type(&field.ty);
 
         tokens.extend(quote! { utoipa::openapi::path::ParameterBuilder::new()